Tag Archives: bacteria

To build appreciation for the science of immunology, we need to find the fun in it.

Many thousands of people spend their lives in windowless laboratories, standing day in and day out, barely speaking to their silent lab mates, often working in a 4°C room, or holding their arms up for hours while they conduct their experiments inside the awkward, but sterile cell culture hood.

Why are they doing this?

They are immunologists. Immunologists address the problems of the immune system that their fellow humans have to live with, like Leukemia, AIDS, allergies and autoimmune disorders. Immunologists use biochemistry, cell biology, molecular biology and genetics to look for ways to help patients and prevent disease.

So, we could simply say that these immunologists are serving their fellow man. But their motivation is not simply to help mankind. Something else drives them to spend those days in a tissue culture hood counting thousands of white blood cells.

Why did these immunologists take the lab path? Why didn’t they become social workers, firemen or even medical doctors? Well, I’ll tell you. Immunology is fun. Immunology involves watching cells identify and destroy other cells. These cells appear to be very similar to every other cell in the universe. These cells have outer membranes, nuclei, DNA and proteins that are almost indistinguishable from every other cell.

The questions are why this particular cell kills bacteria. Why doesn’t this cell kill all types of bacteria? Why does this cell in some people, not kill bacteria? The answers involve making endless comparisons between healthy and sick patients, between pathogenic and non-pathogenic bacteria, between humans and mice and between mice and flies.

So, Immunology is a puzzle. How does the puzzle work? We collect up as many clues as we can, we make a guess, we do an experiment and we try to figure out whether our idea was correct. We compare what we thought would happen to what did happen.

We have tools we can use. And we have rules for addressing these puzzles. We have several paths that others have taken before us that guide our way: We have biochemistry, cell biology, genetics, chemistry and physics. Each of these paths have their own rules and their own tools.

If you could jump in and try out these tools, and attempt a few of the puzzles yourself, then you would understand how immunology works. You would experience the fun! This is what we are doing with Immune Attack 2.0: we are letting you play Immunology… without the hours of standing in a windowless lab.

OK. So why is a scientist at the National Human Genome Research Institute doing research on bacteria? Good question. The answer is that there are so many bacteria living on us and inside of us, that the bacteria affect our bodies a great deal! The bacteria eat and produce waste inside us and on our skin, they interact with our immune cells and our intestines. Just like we have an extensive amount of cell to cell communication among the cells of our body, so are there extensive amounts of communication between bacteria and the cell of our body. Sometimes bacteria alter the behavior of the cells of our body, in ways we used to think were only human-human cell interactions. Additionally, the kind of bacteria that live in and on me may be different from the bacteria that live on someone else. Could that make a difference? It very well could! Obesity or Crohn’s disease may be related to the bacteria in our gut.

First things first, how many bacteria live on us? And how many different kinds of bacteria live on us? Dr. Bonnie Bassler, of Princeton University, gives an estimate of these in her Ted talk, at the 2009 TED Conference. Watch 0:55 through 2:30. (The whole talk is fantastic, too!) Number of human cells in the average adult = 1 trillion. Number of bacteria cells in association with the average adult = 10 trillion. Even more intriguing, is the number of genes that humans have is about 30,000. How many different bacteria genes are associated with us? 300,000!

OK, so there are SIGNIFICANT amounts of bacteria on our bodies, enough to affect us. What are we going to do about it? Well, we could follow the lead of scientists like Bonnie and Julia and start thinking of our associated bacteria genomes as part of our own! And that means, of course, that we need to study them as much as we study ourselves. And this is exactly what Julia Segre’s lab did. Elizabeth Grice, Ph.D., is the first author of the paper, and she is the post doc in Dr. Julia Segre’s lab who lead the work of the paper. Dr. Grice sampled 20 different locations on 10 different people, and found out which different kinds of organisms live in each spot. Each location on our body provides a different climate. Just like plants on the Earth, different bacteria grow better in a dry environment, while others grow better in a wet environment. Elizabeth Grice, Ph.D. and her colleagues are out to find out who lives where. This is basic research. We don’t know yet how valuable this information will be. But on Dr. Segre’s website you can see her research is clearly linked to disease and how to prevent it!

I hope this entry and links helps present the ideas of the world of bacteria, how much smaller and more numerous they are than us, as well as the idea that the things that that occur on the cellular level have big impact in our lives.